Vicinal diol containing monomers and polymers and methods of treating a subterranean formation

ABSTRACT

The present invention provides vicinal diol containing monomers and polymers and methods of preparing and using such monomers and polymers. When crosslinked in aqueous fluids, the polymers form high viscosity gels which are stable at high temperatures.

This is a continuation of application Ser. No. 818,834 filed Jan. 14, 1986 now abandoned.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates generally to vicinal diol containing monomers and polymers. More specifically, this invention provides monomers and polymers containing vicinal diol groups, methods of preparing such monomers and polymers and high viscosity, high temperature stable aqueous gels formed with the polymers which are particularly useful in treating subterranean formations.

2. DESCRIPTION OF THE PRIOR ART

Gelled aqueous fluids are used in a variety of industrial applications to bring about desired results. For example, in the oil industry, gelled aqueous fluids are commonly utilized in carrying out completion, various production stimulation, enhanced production, conformance control and other treatments in subterranean formations containing hydrocarbons. Such gelled aqueous fluids have included both naturally occurring and synthetic water soluble polymer gelling agents as well as agents which cause the polymers to cross-link. The term "aqueous fluid" is used herein to mean any fluid containing some water. The fluid can also contain other components such as alcohols, acids, salts and other miscible or partially miscible substances, gasifiable components such as CO₂ and N₂, and solids.

The naturally occurring polymer gelling agents utilized heretofore include solvatable polysaccharides such as galactomannan gums, glucomannan gums and cellulose derivatives. The synthetic polymer gelling agents include polyacrylate, polymethacrylate, acrylamide-acrylate copolymers, and others. The crosslinking agents utilized include compounds containing multivalent metals which are capable of releasing metal ions in an aqueous fluid such as multivalent metal salts. Examples of the multivalent metal ions are chromium, zirconium, antimony, titanium, iron, tin, zinc and aluminum.

While the heretofore utilized gelled aqueous fluids have been effective at temperatures below about 180° F., at temperatures above about 200° F., and particularly where the aqueous fluids are brines or otherwise contain calcium ions, such gelled aqueous fluids are unstable in that they precipitate or rapidly degrade and revert to thin fluids. Since many subterranean formations requiring procedures or treatments utilizing gelled aqueous fluids exist at temperatures above about 200° F., there is a need for gelled aqueous fluids which are stable at such high temperatures. The terms "stable at high temperatures" and "high temperature stability" are used herein with respect to gelled aqueous fluids to mean that the gelled aqueous fluids retain substantial viscosity for times greater than about 6 to 8 hours at temperatures in the range of from about 180° F. to in excess of 300° F.

By the present invention, monomers containing vicinal diol groups, polymers formed therefrom and high viscosity gelled aqueous fluids formed with such polymers which are stable at high temperatures are provided.

SUMMARY OF THE INVENTION

The present invention provides monomers containing vicinal diol groups having the following structural formula: ##STR1## wherein: R is oxygen or ##STR2## R₁ is hydrogen or methyl; R₃ and R₄ are independently methyl or ethyl;

Y is oxygen or NH;

X⁻ is a halogen, 1/2(SO₄)⁻, CH₃ SO₄ ⁻, C₂ H₃ SO₄ ⁻ or CH₃ COO⁻ ; and

n is 2 or 3.

Methods of preparing such monomers, polymers containing crosslinkable vicinal diol groups, methods of preparing the polymers and methods of forming and using high viscosity gelled aqueous fluids with the polymers are also provided.

DESCRIPTION OF PREFERRED EMBODIMENTS

In accordance with the present invention, water soluble vinyl monomers containing vicinal diol groups are provided having the structural formula: ##STR3## wherein: R is oxygen or ##STR4## R₁ is hydrogen or methyl; R₃ and R₄ are independently methyl or ethyl;

Y is oxygen or NH;

X⁻ is a halogen, 1/2(SO₄)⁻, CH₃ SO₄ ⁻, CH₂ H₃ SO₄ ⁻ or CH₃ COO⁻ ; and

n is 2 or 3.

Vicinal diol containing monomers represented by the above structural formula where R is ##STR5## can be prepared by reacting a water soluble vinyl monomer containing a tertiary amine group with a reactive vicinal diol forming or containing compound. Particularly suitable starting water soluble vinyl monomers containing tertiary amine groups are those having the structural formula: ##STR6## wherein R₁ is hydrogen or methyl, Y is oxygen or NH, R₃ and R₄ are independently methyl or ethyl, and n is 2 or 3. Examples of such monomers are dimethylaminopropylmethacrylamide (hereinafter referred to as DMAPMA), dimethylaminoethylmethacrylamide (hereinafter referred to as DMAEMA), dimethylaminopropylacrylate (hereinafter referred to as DMAPA), dimethylaminoethylmethacrylate (hereinafter referred to as DMAEM), diethylaminoethylmethacrylate (hereinafter referred to as DEAEM) and diethylaminoethylacrylate (hereinafter referred to as DEAEA). Of these, DMAPMA is the most preferred.

Examples of reactive vicinal diol forming or containing compounds which can be utilized are glycidol and 3-halo-1, 2-propanediol compounds such as 3-chloro-1,2-propanediol (α-chlorohydrin) and 3-bromo-1,2-propanediol.

In one technique glycidol, an epoxide, is reacted with the starting vinyl monomer. The nucleophilic amine cleaves the epoxide ring and a proton is consumed in the reaction. Therefore, the addition of a neutralizing acid or other proton source is required as the reaction proceeds. More specifically, the starting vinyl monomer and glycidol reactants are diluted with equal parts of water to make 50% active solutions. The glycidol solution and starting vinyl monomer solution are slowly combined in equal molar amounts while enough of the proton source used, e.g., a 50% by weight acid solution to maintain the pH of the reaction mixture in the range of from about 7.5 to about 12 is simultaneously added. The temperature of the reaction mixture is preferably controlled in the range of from about 10° to 20° C. while the glycidol and proton source are added to the vinyl monomer solution and then raised to about 40° C.

When the starting vinyl monomer is DMAPMA and the proton source is sulfuric acid, the vicinal diol containing monomer formed by the procedure described above is methacrylamidopropyldimethyl-2, 3-dihydroxypropylammonium sulfate (hereinafter referred to as MAPDMDHPAS). The procedure and reaction are represented schematically as follows: ##STR7##

A similar synthesis procedure is to convert the starting amine group containing monomer to the amine salt before reacting it with glycidol. For example, one mole of the starting monomer in a 50% aqueous solution can be combined with one mole of proton source prior to combining glycidol therewith. Glycidol is then combined with the salt formed at a temperature of about 10° to 20° C. followed by raising the temperature to about 40° C. while the reaction goes to completion. When the starting monomer is DMAPMA and the proton source is sulfuric acid, MAPDMDHPAS is formed.

Another synthesis procedure which can be utilized to form the quaternary ammonium type of vicinal diol containing monomer is to react the starting vinyl monomer with 3-halo-1,2-propanediol. For example, a 50% aqueous solution of the starting monomer can be combined with an equal molar quantity of 3-halo-1,2-propanediol at a temperature of about 40° C. to form the vicinal diol containing monomer.

When the starting monomer is DMAPMA and the vicinal diol containing compound is 3-chloro-1,2-propanediol (chlorohydrin), the vicinal diol containing monomer formed is methacrylamidopropyldimethyl-2,3-dihydroxypropylammonium chloride (hereinafter referred to as MAPDMDHPAC). This procedure and reaction are represented schematically as follows: ##STR8##

Vicinal diol containing monomers represented by the above structural formula wherein R is oxygen can be prepared by reacting glycidyl methacrylate (hereinafter referred to as GMA) with a proton source and a hydroxyl group to form 2-3 dihydroxylpropyl methacrylate (hereinafter referred to as DHPMA). The reaction can be carried out in the presence of an acid as a proton source and water as a hydroxyl source.

This procedure and reaction are represented schematically as follows: ##STR9##

In an alternate procedure for forming vicinal diol containing monomers wherein R is oxygen, methacrylic acid (hereinafter referred to as MAA) is reacted with glycidol in the presence of triethylamine (hereinafter referred to as ET₃ N) to form DHPMA. This procedure and reaction are represented schematically as follows: ##STR10##

In another aspect of the present invention, water soluble polymers containing crosslinkable vicinal diol groups are provided. Such polymers can be formed from the vicinal diol containing monomers of this invention described above. That is, a vicinal diol containing vinyl monomer is polymerized with one or more other monomers to form a high molecular weight (above about 100,000) polymer containing crosslinkable vicinal diol groups. The polymerization reaction can be carried out utilizing known water-in-oil emulsion techniques or aqueous solution techniques.

Examples of monomers which can be utilized with the vicinal diol containing monomers in the polymerization reaction to form copolymers or terpolymers are DMAPMA, methacrylamidopropyltrimethylammonium chloride (hereinafter referred to as MAPTAC), N,N-dimethylacrylamide (hereinafter referred to as NNDMA), acrylamide, methacrylamide, 2-acrylamido-2-methylpropanesulfonic acid (hereinafter referred to as AMPS), sodium styrene sulfonate, N-vinyl-2-pyrrolidone and acrylic acid. Preferably, the vicinal diol containing vinyl monomer MAPDMDHPAS is polymerized with NNDMA to form a copolymer with a mole ratio of 9 moles of NNDMA to 1 mole of MAPDMDHPAS. However, other copolymers and terpolymers of other mole ratios using a variety of other monomers can be formed and utilized in accordance with this invention as illustrated in the examples which follow.

In an alternate procedure for forming the vicinal diol containing polymers of this invention, a polymer starting material can be reacted with glycidol to add the vicinal diol group to the polymer. For example, a copolymer of DMAEM and acrylamide can be reacted with glycidol at a pH of about 10 to form a vicinal diol containing polymer equivalent to a polymer containing equivalent mole amounts of acrylamide, DMAEM and the quaternization product of DMAEM and glycidol formed from monomer starting materials.

As mentioned above, the polymers of this invention containing vicinal diol groups are water soluble and hydrate in aqueous fluids. Upon being crosslinked by way of the diol groups, a high viscosity, high temperature stable, crosslinked aqueous fluid results.

In forming a high viscosity gelled aqueous fluid of this invention which is stable at high temperatures, a polymer containing crosslinkable vicinal diol groups is dissolved in an aqueous fluid. Generally, the polymer is dissolved in the aqueous fluid in an amount in the range of from about 0.004 to about 0.8 pounds of active polymer per gallon of solution, preferably in the range of from about 0.02 to about 0.08 pounds per gallon of solution. A crosslinking agent is combined with the aqueous fluid-polymer solution to thereby crosslink the vicinal diol groups of the polymer whereby a high viscosity, high temperature stable, gelled aqueous fluid is formed. The crosslinking agent is combined with the aqueous fluid-polymer solution in an amount in the range of from about 0.001 pounds/gallon of solution to about 0.2 pounds/gallon of solution.

The crosslinking agents that can be utilized in the present invention can generally be described as water soluble salts and complexes of multivalent cations which are capable of forming a crosslinked gel with vicinal diol groups of the polymer. Examples of the multivalent metal cations are zirconium, antimony, titanium, iron, tin, chromium and aluminum. In addition to the metal cations, boron can be utilized as a crosslinking agent. Particularly preferred such crosslinking agents are zirconium salts, such as zirconium lactate, zirconium acetate, and zirconium oxychloride, chrome citrate, and titanium triethanolamine, the most preferred being a zirconium lactate crosslinking composition.

A particularly suitable zirconium lactate crosslinking composition can be prepared by adding about 2 moles of lactic acid to a quantity of water sufficient to allow mixing of ingredients and adjusting the pH of the resulting acid solution to about 7 with ammonium hydroxide. About one mole of zirconium metal ion having a valence of +4, preferably as zirconium oxychloride, is then added to the solution to form the crosslinking composition.

Another similar suitable zirconium lactate crosslinking composition includes 2 moles of triethanolamine in addition to the lactic acid and zirconium oxychloride added at a pH of about 7.

The high viscosity, high temperature stable, gelled aqueous fluids formed in accordance with the present invention utilizing polymers containing vicinal diol groups are particularly suitable for carrying out completion, stimulation, enhanced production and other treatments in high temperature subterranean formations, e.g., formations existing at temperatures above about 180° F. Examples of such treatments where high viscosity gelled aqueous fluids are utilized are treatments for consolidating loose sands in formations, acidizing formations, fracturing formations, and enhancing production from formations. In accordance with the present invention, such treatments and others are carried out in high temperature subterrenean formations by contacting the formations with highly viscous aqueous gels comprised of aqueous fluids, water soluble polymers containing vicinal diol groups of the present invention and crosslinking agents.

To further illustrate the present invention and facilitate a clear understanding thereof, the following examples are given.

EXAMPLE 1

A water soluble vicinal diol containing vinyl monomer (MAPDMDHPAS) is prepared from DMAPMA and glycidol starting materials as follows.

170.26 g (1 mole) of dimethylaminopropylmethacrylamide (DMAPMA) are placed in a glass vessel containing a magnetic stirrer and mixed with 294.91 g of deionized water. Two addition funnels are suspended above the vessel; one containing 75.6 g of glycidol and the other containing 49.05 g of concentrated H₂ SO₄. The pH and temperature of the reaction mixture are monitored continuously while the H₂ SO₄ is added dropwise over a period of about 30 minutes. Prior to the H₂ SO₄ addition, the solution is cooled to 19° C. and the solution has a pH of 11.3. After the H₂ SO₄ addition, the solution is cooled to 15° C. and has a pH of 7.5. The glycidol is next added dropwise and the vessel is warmed to about 21° C. using a hotplate. The glycidol addition time is 1 hour and 35 minutes and the final pH is 7.41. The reaction mixture is heated to and maintained at 40° C. for 40 hours. The final pH is 9.5. Analysis of the reaction indicates a trace of DMAPMA along with MAPDMDHPAS monomer.

The structure of the synthesized MAPDMDHPAS monomer is indicated to be as follows: ##STR11##

EXAMPLE 2

DHPMA is prepared by placing 10 g of concentrated sulfuric acid in 80 g of deionized water. 90 g of GMA are slowly added to the acid solutions while being stirred. The reaction mixture gradually increases in temperature to 180° F. The solution is then placed in an ice bath to maintain the reaction temperature between 74° and 180° F. This procedure is continued until all GMA is added. The resulting DHPMA monomer is then ready for use.

EXAMPLE 3

DHPMA is prepared by placing the following materials in a 100 ml round bottom flask with side arm, condensor, and addition funnel:

10.5 g methacrylic acid

0.03 g hydroquinone

0.41 ml ET₃ N (triethylamine with micropipette).

The flask and contents are heated in an oil bath to 118° C. and then cooled to 114.5° C. 7.43 g glycidol are next added to the flask. The glycidol is added at a one-drop per 4-5 second rate over the next 10-minute period while keeping the temperature at 115°-116° C. The reaction product in the flask changes from clear to slight yellow in color during addition and is slowly cooled to 89° C. during the next 15 minutes. Vacuum is applied until boiling commences at 83° C. After the boiling stops the temperature is raised to 95°-100° C. and boiling and vacuum are again continued for one hour to remove excess acid. An NMR analysis of the final reaction mixture reveals that 2,3-dihydroxypropylmethacrylate is the major component.

EXAMPLE 4

Homopolymers, copolymers and terpolymers are prepared using the vicinal diol containing monomer (MAPDMDHPAS) prepared as described in Example 1 and other monomers. A water-in-oil emulsion technique is used which is illustrated by the following procedure wherein a copolymer of acrylamide (90 mole %) and MAPDMDHPAS (10 mole %) is prepared.

The following ingredients are mixed with stirring until homogeneous to form an aqueous phase:

    ______________________________________                                         50% aqueous MAPDMDHPAS 58.67     g                                             46% aqueous acrylamide 139.23    g                                             deionized water        20.0      g                                             ethylenediamine tetracetic acid,                                                                      .05       g                                             disodium salt, dihydrate (Na.sub.2 EDTA)                                       sodium chloride        6.0       g                                             ______________________________________                                    

The pH of the aqueous phase is adjusted to 7.42 with 0.15 ml 50% NaOH.

The following ingredients are mixed to form an oil phase.

    ______________________________________                                         a mixture of isoparaffinic hydrocarbons                                                                   81 g                                                (ISOPAR M)                                                                     sorbitan monooleate         6 g                                                ______________________________________                                    

The oil phase is added to a 500 ml Waring blendor jar fitted with a lid containing two openings for an N₂ inlet tube and an addition funnel. The oil phase and waring blendor jar are sparged with N₂ gas. The aqueous phase is introduced into the oil phase over a 11/2 minute period while stirring at about 4000 rpm. The resulting emulsion is stirred for an additional 5 minutes at the same rate.

The emulsion is added to a presparged one-liter glass kettle fitted with a stirrer, a N₂ inlet tube, a N₂ exit tube, and a thermocouple probe with a digital readout. The water-in-oil comonomer emulsion is stirred at an rpm of from about 500 to about 1500 and sparged with N₂ gas while heating to 40° C. in about 30 minutes, followed by the addition of 0.2 g sodium bisulfite. Stirring and sparging are continued while maintaining the temperature at about 40° C. for 15 minutes, followed by the addition of 0.1 g 2,2'-azobis(2,4dimethylvaleronitrile) initiator. After about 45 minutes, a mild exotherm starts which continues for about 3 hours. The temperature is maintained for one additional hour and an additional 0.1 g of 2,2 -azobis(2,4dimethylvaleronitrile) is added. The temperature is increased to about 60° C. and held for about one hour after which the emulsion is cooled to room temperature. This emulsion is homogeneous and stable.

The inversion of the emulsion is caused by adding 3.33 g of the emulsion to a Waring blendor containing 100 g of API brine and 0.3 ml of a 50% solution of dimethylbenzyltallow ammonium chloride "API brine" is a laboratory brine formulation comprised of 1350 g NaCl and 150 g CaCl₂ dissolved in 13500 g of deionized water and filtered through E-D grade 617 filter paper or equivalent. Inversion of the polymer into the brine occurs in seconds as evidenced by a large increase in viscosity.

A number of polymers are prepared utilizing the general procedure described above. The identification of the polymers and synthesis reaction conditions involved are set forth in Tables I and II below.

The polymers are identified using a code that gives the mole % of the various monomers used in their preparation. That is, three numbers are used (0.0.0) representing, in order, mole % acrylamide, mole % NNDMA, and mole % of a termonomer. These are followed by a letter which represents the termonomer or a monomer substituted for the NNDMA, where A is dimethylaminopropylmethacrylamide (DMAPMA), DS is methacrylamidopropyldimethyl-2, 3-dihydroxypropylammonium sulfate (MAPDMDHPAS), DC is methacrylamidopropyldimethyl-2,3-dihydroxypropyl ammonium chloride (MAPDMDHPAC), Q is methacrylamidopropyltrimethyl ammonium chloride (MAPTAC) and M is methacrylamide. Sometimes a fourth number is used which represents the particular polymer synthesis. The presence of a P indicates that it is an emulsion polymer. The presence of a K or the absence of P indicates a solution polymer. The number of the polymer sometimes follows the P in the polymer identification code.

                                      TABLE I                                      __________________________________________________________________________     Polymer Synthesis Mole % of Monomer Feed                                       Polymer                                                                             Polymer                                       Polymer                     No.  Identification                                                                          Monomer 1                                                                            Mole %                                                                              Monomer 2 Mole %                                                                              Monomer 3                                                                            Mole %                                                                              Activity                    __________________________________________________________________________                                                        %                           1-5  90.0.10Q.P1-5                                                                           AcAm  90   MAPTAC    10   --    --   30.6                         6   90.0.10DC.P6                                                                            AcAm  90   MAPDMDHPAC                                                                               10   --    --   30.6                         7   90.0.100A.P7                                                                            AcAm  90   DMAPMA    10   --    --   29.9                         8   90.0.10A.P8                                                                             AcAm  90   DMAPMA.1/2H.sub.2 SO.sub.4                                                               10   --    --   30.6                         9   90.0.10DS.P9                                                                            AcAm  90   MAPDMDHPAS                                                                               10   --    --   31.0                        10   90.3.0.9.7DS.P10                                                                        AcAm    90.3                                                                              MAPDMDHPAS                                                                                 9.7                                                                               --    --   31.5                        11   100.0.0.P11                                                                             AcAm  100    --      --   --    --   30.7                        12   0.0.100DS.P12                                                                           --    --   MAPDMDHPAS                                                                               100  --    --   30.6                        13   50.0.50DS.P13                                                                           AcAm  50   MAPDMDHPAS                                                                               50   --    --   32.8                        14   90.0.10DS.P14                                                                           AcAm  90   MAPDMDHPAS                                                                               10   --    --   25.0                        15   80.0.20DS.P15                                                                           AcAm  80   MAPDMDHPAS                                                                               20   --    --   30.0                        16   80.0.20DS.P16                                                                           AcAm  80   MAPDMDHPAS                                                                               20   --    --   30.8                        17   90.0.10DS.P17                                                                           AcAm  90   MAPDMDHPAS                                                                               10   --    --   30.0                        18   50.40M.10DS.P18                                                                         AcAm  50   MAPDMDHPAS                                                                               10   MAA   40   30.0                        19   90.0.10Q.P19                                                                            AcAm  90   MAPTAC    10   --    --   30.0                        20   90.0.10DS.P20                                                                           AcAm  90   MAPDMDHPAS                                                                               10   --    --   30.0                        21   80.10Q.10DS.P21                                                                         AcAm  80   MAPDMDHPAS                                                                               10   MAPTAC                                                                               10   30.0                        __________________________________________________________________________      AcAm--Acrylamide                                                               MAPTAC--Methacrylamidopropyltrimethylammonium chloride                         MAPDMDHPAC--Methacrylamidopropyldimethyldihydroxypropylammonium chloride       DMAPMA--Dimethylaminopropylmethacrylamide                                      MAPDMDHPAS--Methacrylamidopropyldimethyldihydroxypropylammonium sulfate        MAA--Methacrylamide                                                      

                                      TABLE II                                     __________________________________________________________________________     Polymer Synthesis Reaction Conditions                                                                             Isoparaffinic                                                                          Sorbitan                            Polymer                                                                             Monomers        Na.sub.2,                                                                               NaHSO.sub.3                                                                         Hydrocarbons                                                                           Monooleate                                                                           Initiator.sup.1                                                                     Temp.                                                                               Time                No.  (g)   H.sub.2 O (g)                                                                       NaCl (g)                                                                            EDTA (g)                                                                             pH (g)  (Isopar M) (g)                                                                         (g)   (g)  (°C.)                                                                        Hours               __________________________________________________________________________      1   172.3 208.3                                                                               --   .1    4.7                                                                               --   162     18.4  .5   49-51                                                                               2                    2   86.15 104  --   .05   4.7                                                                                .25 81      9.2   .25 + .25                                                                           50-60                                                                               4                    3   86.39 104  --   .1    4.7                                                                               .1   81      9.2   .25  50-60                                                                               2                    4   86.39 104  --   .05   4.7                                                                               .4   81      9.2   .25 + .1                                                                            50-53                                                                               3                    5   86.20 104.15                                                                              --   .05   4.6                                                                               .5   81      9.2   .25 + .25                                                                           46-62                                                                               4                    6   86.20 104.15                                                                              --   .05   7.8                                                                                .25 81      9.2   .25  45-51                                                                               3                    .sup. 7.sup.2                                                                      81.14 99.1 --   .05   10.1                                                                              .5   81      9.2   .25  45-90                                                                               4                    8   85.95 103.9                                                                               0.2  .05   -- --   81      9.2   .25  45                                                                                  3+-. .3              9   93.39 111.34                                                                              0.2  .05   4.9                                                                               --   81      9.2   .25  45                                                                                  3+-. .3             10   92.37 110.32                                                                              0.2  .05   4.9                                                                               --   81      9.2   .20  45                                                                                  4+-. .3             11   91.03 106.87                                                                              0.2  .05   4.8                                                                               --   81      9.2   .20  45                                                                                  3+-. .4             .sup. 12.sup.3                                                                      91.0  113.74                                                                              0.2  .05   4.9                                                                               .4   81      9.2   .20  45                                                                                  4+-. .3             13   91.11 96.14                                                                               0.2  .05   4.9                                                                               --   81      9.2   .20  45                                                                                  3+-. .2             14   93.39 111.34                                                                              20.  .05   7.8                                                                               --   81      9.2   .1 + .1                                                                             40.6-                                                                               53.7                .sup. 15.sup.3                                                                      115.53                                                                               169.31                                                                              10.  .05   8.9                                                                                .35 81      9.2   .1 + .1                                                                             45-50                                                                               6                   16   115.53                                                                               156.82                                                                              10.  .05   7.7                                                                               .3   81      9.2   .1 + .1                                                                             40.7-                                                                               82.7                17   93.39 124.47                                                                              6.   .05   7.5                                                                               .2   81      6     .1 + .1                                                                             42-45                                                                               7                   18   98.88 137.06                                                                              6.   .05   7.9                                                                               .2   81      6     .2 + .2                                                                             41-49                                                                               6                   19   86.20 107.65                                                                              6.   .05   8.3                                                                               .2   81      6     .1 + .1                                                                             40-45                                                                               4                   20   93.39 124.46                                                                              6.   .05   7.4                                                                               .2   81      6     .1 + .1                                                                             37-41                                                                               6                   21   108.28                                                                               159.26                                                                              6.   .05   7.6                                                                               .2   81      6     .1 + .1                                                                             39-43                    __________________________________________________________________________      .sup.1 2,2' Azobis (2,4dimethylvaleronitrile); +means 2 separate addition      .sup.2 Reaction exotherm uncontrollable                                        .sup.3 Reaction incomplete, little to no exotherm                        

The polymers described above can be prepared using a solution technique instead of the water-in-oil emulsion technique. The solution technique involves reacting the monomers with initiators and buffer in an aqueous solution in the absence of oxygen. A reaction pH in the range of from about 6 to about 9 and a reaction temperature in the range of from about 32° F. to about 120° F. can be utilized to form the polymer solution.

EXAMPLE 5

The polymer emulsions formed as described in Example 4 are inverted in API brine, hydrated, crosslinked and evaluated for stability at 250° F.

EMULSION INVERSION AND POLYMER HYDRATION

A quantity of API brine is placed in a Waring blendor jar and mixed at low speed. An inverter such as a 50% by weight aqueous solution of dimethylbenzyltallow ammonium chloride is added in an amount of 10% by weight of emulsion to be inverted. The mixing rate is increased to about 1500 rpm and the amount of polymer emulsion used is added and mixed for one minute. The resulting viscosity is measured on a Model 35 FANN VG Meter with No. 1 spring and standard bob and sleeve to determine when complete hydration has occurred. For example, 300 ml of API brine are added to a one-liter Waring blendor jar and mixed at a low rate followed by adding one ml of the above-described inverter. Ten grams of polymer emulsion are added while mixing at 1500 rpm. Mixing is continued for one minute and viscosity is measured.

The results of these tests are shown in Table III.

                  TABLE III                                                        ______________________________________                                         Viscosity Properties of Inverted Polymers                                      Polymer Concentration: 1% by Weight of Fluid                                   Temperature: Ambient Conditions                                                       Steady State                                                                   FANN Dial Readings @ 100, 200 and 300 rpm                               Polymer  Deionized Water                                                                               API Brine                                              No.      100    200      300  100    200  300                                  ______________________________________                                          8       84     116      141  17     27   35                                    9       71     101      126   7     12   16                                   10       74     107      137   7     11   14                                   11       47     62       78   51     72   91                                   13       92     126      152   4      7    9                                   14       50     75       93   19     28   37                                   16       61     91       115  12     19   25                                   17       48     66       80   28     42   53                                   18       15     25       33   13     21   29                                   19       53     69       82   40     57   72                                   20       55     75       91   29     44   56                                   21       53     72       86   28     41   53                                   ______________________________________                                    

F. TEMPERATURE STABILITY

100 g of the hydrated polymer are placed in a glass pressure vessel. A desired amount of crosslinker such as 0.2% zirconium oxychloride is added to the vessel. The vessel is sealed and agitated to thoroughly mix the polymer and crosslinker. The vessel is then heated to the desired temperature by placing it in a heated oil bath. At desired intervals the sample is inspected and the stability of the crosslinked polymer visually noted.

The results of these tests are given in Table IV below.

                                      TABLE IV                                     __________________________________________________________________________     Crosslinked Polymer Stability at 250° F.                                Polymer Concentration: 1% Base Fluid: API Brine                                Polymer                                                                             N.sub.2.sup.1                                                                       Crosslinker                                                          No.  Purged                                                                              Name     %.sup.2                                                                            Stability hrs.sup.3                                                                   Final pH.sup.4                                                                       Observations                               __________________________________________________________________________     .sup. 21.sup.5                                                                      No   Potassium                                                                               0.4 <24    8.4   homogeneous - no crosslinked gel                     Pyroantimonate                                                       21   No   Formic Acid                                                                             0.1              homogeneous - no crosslinked gel                     Potassium                                                                               0.4 <24    4.2                                                        Pyroantimonate                                                       21   No   Potassium                                                                               0.4              homogeneous - crosslinked gel @ 48                                             hrs.                                                 Pyroantimonate                                                                 Zicronium                                                                               0.1 >48<96 8.1                                                        Oxychloride                                                          .sup. 20.sup.6                                                                      No   Potassium                                                                               0.4 <24    8.4   homogeneous - no crosslinked gel                     Pyroantimonate                                                       20   No   Formic Acid                                                                             0.1              homogeneous - no crosslinked gel                     Potassium                                                                               0.4 <24    4.5                                                        Pyroantimonate                                                       20   No   Potassium                                                                               0.4              homogeneous - crosslinked gel @ 48                                             hrs.                                                 Pyroantimonate                                                                 Zirconium                                                                               0.1 >48<96 7.8                                                        Oxychloride                                                          .sup. 19.sup.7                                                                      No   Potassium                                                                               0.4 <24    8.3   homogeneous - no crosslinked gel                     Pyroantimonate                                                       19   No   Formic Acid                                                                             0.1              homogeneous - no crosslinked gel                     Potassium                                                                               0.4 <24    4.4                                                        Pyroantimonate                                                       19   No   Potassium                                                                               0.4              homogeneous - less viscosity than                    Pyroantimonate            21 or 20                                             Zirconium                                                                               0.1 >48<96 7.4                                                        Oxychloride                                                          21   No   Zirconium                                                                               0.2 >72    6.0   crosslinked gel - some free H.sub.2                                            O                                                    Oxychloride                                                          21   No   Zirconium                                                                               0.2 <16    8.5.sup.8                                                                            gel separated                                        Oxychloride                                                          21   No   Zirconium                                                                               0.3 >48<72 8.0   crosslinked gel - 1/2 free H.sub.2 O                 Lactate with                                                                   Triethanolamine                                                      21   No   Zirconium                                                                               0.3 >24<48 8.7.sup.8                                                                            slight crosslink - free H.sub.2 O                    Lactate with                                                                   Triethanolamine                                                      20   No   Zirconium                                                                               0.2 >48<72 6.3   rigid crosslinked gel 1/2 48 hrs.                    Oxychloride                                                          20   No   Zirconium                                                                               0.2 <16    8.4.sup.8                                                                            no crosslink - phase separation                      Oxychloride                                                          20   No   Zirconium                                                                               0.3 >24<48 8.1   slight crosslink - rehealed on                                                 cooling                                              Lactate with                                                                   Triethanolamine                                                      20   No   Zirconium                                                                               0.3 >24<48 8.7.sup.8                                                                            slightly better than above gel                       Lactate with                                                                   Triethanolamine                                                      19   No   Zirconium                                                                               0.2 >24<48 5.3   crosslinked gel - 1/2 free H.sub.2 O                 Oxychloride                                                          19   No   Zirconium                                                                               0.2 <16    8.3.sup.8                                                                            homogeneous - no crosslinked gel                     Oxychloride                                                          19   No   Zirconium                                                                               0.3 >16<24 8.0   homogeneous - no crosslinked gel                     Lactate with                                                                   Triethanolamine                                                      19   No   Zirconium                                                                               0.3 <16    8.7.sup.8                                                                            homogeneous - no crosslinked gel                     Lactate with                                                                   Triethanolamine                                                      18   Yes  Zirconium                                                                               0.1 <19    --    polymer flocculated                                  Oxychloride                                                          18   Yes  Zirconium                                                                               0.2 <19    --    polymer flocculated                                  Oxychloride                                                          18   Yes  Zirconium                                                                               0.1 >48<72 --    polymer separated - best @ 72 hrs.                   Lactate                                                              18   Yes  Zirconium                                                                               0.2 >48<72 --    polymer separated                                    Lactate                                                              18   Yes  Zirconium                                                                               0.3 >48<72 --    polymer separated - best at 48 hrs.                  Lactate                                                              18   Yes  Zirconium                                                                               0.2 <19          polymer flocculated                                  Acetate                                                              17   Yes  Zirconium                                                                               0.1 >72<144      rigid crosslinked gel @ 72 hrs.                      Oxychloride                                                          17   Yes  Zirconium                                                                               0.2 >72<144      same as above - trace free H.sub.2 O                 Oxychloride                                                          17   Yes  Zirconium                                                                               0.1 >72<144      slight crosslinked gel - trace free                                            H.sub.2 O                                            Lactate                                                              17   Yes  Zirconium                                                                               0.2 >72<144      moderate crosslinked gel - trace free                                          H.sub.2 O                                            Lactate                                                              17   Yes  Zirconium                                                                               0.3 >72<144      rigid crosslinked gel - trace free                                             H.sub.2 O                                            Lactate                                                              17   Yes  Zirconium                                                                               0.2 >72<144      less rigid than above test                           Acetate                   polymer flocculated - free H.sub.2 O       18   Yes  Zirconium                                                                               0.1 >6<24                                                             Lactate with                                                                   Triethanolamine                                                      18   Yes  Zirconium                                                                               0.2 >6           sample lost, broke sample jar                        Lactate with                                                                   Triethanolamine                                                      18   Yes  Zirconium                                                                               0.3 >24<48       more flocculated polymer than above                  Lactate with                                                                   Triethanolamine                                                      17   Yes  Zirconium                                                                               0.2 >72          crosslinked gel - free H.sub.2 O                     Lactate with                                                                   Triethanolamine                                                      17   Yes  Zirconium                                                                               0.3 >72          weak crosslinked gel - free H.sub.2                                            O                                                    Lactate with                                                                   Triethanolamine                                                      17   Yes  Zirconium                                                                               0.4 >72          same as above with less free H.sub.2                                           O                                                    Lactate with                                                                   Triethanolamine                                                      13   Yes  Zirconium                                                                               0.3  --          no indication of crosslink - base                                              gel                                                  Lactate with                                                                   viscosity 7 cps                                                                Triethanolamine                                                      13   Yes  Zirconium                                                                               0.6  --          no indication of crosslink - base                                              gel                                                  Lactate with                                                                   viscosity 7 cps                                                                Triethanolamine                                                      16   Yes  Zirconium                                                                               0.3 >1<66        poor crosslink - base gel viscosity                                            12 cps                                               Lactate with                                                                   Triethanolamine                                                      16   Yes  Zirconium                                                                               0.6 >1<66        poor crosslink - base gel viscosity                                            12 cps                                               Lactate with                                                                   Triethanolamine                                                      17   Yes  Zirconium                                                                               0.3 >96<240      crosslinked gel with free H.sub.2 O @                                          96 hrs.                                              Lactate with                                                                   Triethanolamine                                                      17   Yes  Zirconium                                                                               0.3 >1<66        overcrosslinked - majority free                                                H.sub.2 O                                            Oxychloride                                                          17   Yes  Zirconium                                                                               0.6 >1<66        same as above test                                   Oxychloride                                                          18   Yes  Zirconium                                                                               0.3 >1<66        crosslinked gel with free H.sub.2 O @                                          66 hrs.                                              Lactate with                                                                   Triethanolamine                                                      18   Yes  Zirconium                                                                               0.6 >1<66        same as above test                                   Lactate with                                                                   Triethanolamine                                                      18   Yes  Zirconium                                                                               0.3 >1<66        majority free H.sub.2 O with                                                   crosslinked gel                                      Oxychloride                                                          __________________________________________________________________________      .sup.1 to reduce oxygen level N.sub.2 was bubbled through gels and             pressure vessels were purged                                                   .sup.2 % = volume % based on total weight of gel                               .sup.3 stability hrs.  the majority of the gel had some crosslinked            character. Some free H.sub.2 O may be present. No precipitate noted.           .sup.4 final pH  pH was obtained after test was completed and sample           cooled to ambient condition                                                    .sup.5 initial pH of base gel 6.73                                             .sup.6 initial pH of base gel 7.0                                              .sup.7 initial pH of base gel 6.9                                              .sup.8 pH adjusted to this value with NaOH                               

Steady state viscosity properties of polymers 8 through 21 in deionized water and API brine are shown in Table III. The relative molecular weights and degrees of ionic character of the prepared copolymers are utilized to evaluate the synthesis conditions. Viscosity properties in deionized water are a function of molecular weight and degree of ionic character while the viscosity difference in these two base fluids is predominantly a function of the degree of ionic character.

Preliminary stability data at 250° F. for several polymers crosslinked with various metal crosslinkers are presented in Table IV. Gel stability is dependent upon the polymer, crosslinker, crosslinker concentration, pH and oxygen content. In general, the most stable gels are formed with polymers 17, 20 and 21 when crosslinked with 0.1 or 0.2% of zirconium oxychloride or 0.3% of zirconium lactate with triethanolamine.

EXAMPLE 6

Vinyl monomers containing vicinal diol groups are prepared as follows.

A. Methacrylamidopropyldimethyl-2,3-dihydroxypropylammonium sulfate (MAPDMDAPAS)

To a 1-liter glass beaker containing a magnetic stirrer is added 170.26 g (1 mole) of DMAPMA and 170.26 g of deionized water while stirring. Initial pH and temperature are 11.2° and 23.1° C., respectively. Two addition funnels are suspended above the beaker; one contains 75.6 g (1 mole) of glycidol and the other contains 98.2 g of 50% H₂ SO₄. The pH and temperature are monitored continuously during the drop-wise addition of glycidol. Temperature is maintained between 19.5° and 27.5° C. by placing the beaker in an ice bath. The pH is maintained between 10.6 and 11.2 by adding 50% H₂ SO₄ as needed. All of the glycidol is added within 1 hour and 4 minutes. An additional 75.6 g of water is added to the reaction mixture; a portion is flowed through the addition funnel which contained the glycidol and the remainder is added to the addition funnel containing the remaining H₂ SO₄. The ice bath surrounding the reaction vessel is removed and replaced with a warm water bath in order to raise the reaction temperature to 40° C. The remaining acid and water mixture is added to the reaction vessel over a period of 2 hours and 41 minutes. During this stepwise addition the temperature is held at about 40° C. and the pH is maintained between 11.3 and 10.1 until the last portion of acid is added. The final pH is 4.55. The reaction mixture is then placed in a sealed brown bottle and submerged in a 42° C. bath. The reaction mixture is removed at 16 hours. The final pH of the product is 5.2 at room temperature.

B. Methacrylamidopropyldimethyl-2,3-dihydroxypropylammonium chloride (MAPDMDHPAC)

To a 1-quart brown bottle is added 170.3 g (1 mole) DMAPMA and 280.8 g of deionized water. Mixing is accomplished by swirling the bottle. To this mixture is added 110.5 g (1 mole) of 3-chloro-1,2-propanediol. A small exotherm is observed. The sealed bottle containing the reaction mixture is submerged in a water bath controlled to about 40° C. After reacting at this temperature for 20 hours the reaction mixture is removed.

The quaternary ammonium chloride monomer (prepared according to Procedure B) is formed by substitution of the chloride of α-chlorohydrin with the nitrogen of the tertiary amine. The quantity of chloride ion produced during the reaction is determined by titration with silver nitrate. Based on this analysis, it is calculated that 99.6% of the α-chlorohydrin is reacted and therefore, the percent of conversion is 99.6%.

The vicinal diol content of MAPDMDHPAS and MAPDMDHPAC are determined to be 53.0% and 50.6%, respectively. The theoretical diol content of each monomer is 50.0%, since each is prepared as a 50% aqueous solution.

EXAMPLE 7

A variety of polymers containing vicinal diol groups are prepared. The polymers are hydrated and the resulting gels are evaluated for stability at high temperature. The hydrated polymers are then crosslinked and evaluated for stability at high temperatures.

Thermal stability tests of hydrated emulsion polymers at 250° F. in API brine are summarized in Tables V and VI. Thermal stability tests of hydrated solution polymers at 280° F. in API brine are summarized in Tables V and VI. Thermal stability tests of hydrated solution polymers at 280° F. in API brine are summarized in Table VII. The solution polymers are prepared by reacting the starting materials and initiators in a 2% potassium chloride solution.

PROCEDURE

To obtain a 100 g sample of hydrated polymer gel, 97.7 g of deionized water is added to a 500 ml Waring blendor. An inverter such as a 50% by weight aqueous solution of dimethylbenzyltallowammonium chloride is added in an amount of 0.33 ml to the water with gentle mixing. The emulsion polymer (3.33 g) is quickly added with a syringe while mixing at about 1500 rpm. Mixing is continued for 2 minutes. The sample is left static at least one hour at ambient temperature to fully hydrate before use or evaluation.

A 100 g sample of hydrated base gel is placed in an 8 oz. glass jar. The sample is purged 30 minutes by bubbling N₂ through the sample. The jar is sealed and then placed inside a purged pressure vessel. The vessel is placed into an oil bath at the desired temperature for the required time period. The vessel is then removed and cooled to ambient temperature. The sample is removed and evaluated. Data such as pH, viscosity and gel condition are recorded.

                  TABLE V                                                          ______________________________________                                         Thermal Stability of 1% Emulsion                                               Polymers at 250° F. in API Brine                                                   Initial*  Final*   Time at Viscosity                                           Viscosity Viscosity                                                                               250° F.                                                                         Retained                                 Polymer    (cp)      (cp)     (days)  (%)                                      ______________________________________                                         80.10Q.10DS.P21                                                                           200       12.0     2.25    6                                        50.40.10DS.P24                                                                            85        19.0     5.0     22                                       50.40.10DS.P24                                                                            85        7.5      12.0    9                                        50.40Q.10DS.P23                                                                           75        6.5      5.0     9                                        50.40Q.10DS.P25                                                                           85        10.0     5.0     12                                       90.0.10DS.P20        19.0     2.25                                             90.0.10Q.P19         6.0      2.25                                             ______________________________________                                          *Viscosity measured on a Brookfield LVT using a number 1 spindle at 6 rpm

                  TABLE VI                                                         ______________________________________                                         Thermal Stability of 1% Emulsion Polymers in API Brine                                                            Tem- Time at                                          Initial* Final*   Retained                                                                              pera-                                                                               Temper-                                          Viscosity                                                                               Viscosity                                                                               Viscosity                                                                             ture ature                                  Polymer   (cp)     (cp)     (%)    (°F.)                                                                        (days)                                 ______________________________________                                         70.20.10DS.P43                                                                           130      20       14     250  5.0                                    70.20.10DS.P43                                                                           130      55       42     250  7.0                                    70.20.10DS.P43                                                                           130      150      115    250  10.0                                   50.40.10DS.P41                                                                           272      826       304** 280  0.9                                    50.40.10DS.P41                                                                           345      30        8     280  0.9                                    50.40.10DS.P40                                                                           180      130      72     250  3                                      50.40.10DS.P40                                                                           180      100      56     250  5                                      50.40.10DS.P40                                                                           180      35       20     250  7                                      50.40.10DS.P40                                                                           180      10        6     250  10                                     50.40.10DS.P41                                                                           190      230      120    250  3                                      50.40.10DS.P41                                                                           190      65       34     250  5                                      50.40.10DS.P41                                                                           190      21       11     250  7                                      50.40.10DS.P41                                                                           190      25       13     250  10                                     60.30.10DS.P42                                                                           150      100      67     250  3                                      60.30.10DS.P42                                                                           150      25       17     250  5                                      60.30.10DS.P42                                                                           150      30       20     250  7                                      ______________________________________                                          *Viscosity measured on a Brookfield LVT using a number 1 spindle at 6 rpm      **Sample believed to be contaminated with metal ions during test.        

                  TABLE VII                                                        ______________________________________                                         Thermal Stability of 1% Solution Polymers                                      at 280° F. in API Brine for 22 Hours                                                Initial*    Final*   Viscosity                                                 Viscosity   Viscosity                                                                               Retained                                      Polymer     (cp)        (cp)     (%)                                           ______________________________________                                         75.20.5DS.9K                                                                               617         320      52                                            70.20.10DS.7K                                                                              87          49       56                                            70.20.10DS.76                                                                              58          54       93                                            70.20.10DS.7K                                                                              101         42       42                                            70.20.10Q.80                                                                               121         79       65                                            70.20.10Q.80                                                                               119         26       22                                            70.20.10Q.78                                                                               94          43       46                                            70.20.10A.106                                                                              67          28       42                                            50.40.10DS.8K                                                                              74          49       66                                            50.40.10DS.8K                                                                              78          47       60                                            50.40.10DS.8K                                                                              82          44       54                                            0.90.10DS.87                                                                               36          55       152                                           0.90.10DS.12K                                                                              25          24       96                                            0.90.10DS.12K                                                                              24          23       96                                            0.90.10DS.12K                                                                              21          16       76                                            ______________________________________                                          *Viscosity measured on a Brookfield LVT using a number 1 spindle at 6 rpm                                                                               

Tables V, VI and VII show the superiority of the 0.90.10DS polymer formulation over other polymer formulations. The stability testing of inverse emulsion polymers at 250° and 280° F. shows a loss of viscosity with time except in the case of 70.20.10DS.P43 (see Table IV). This polymer at 1% concentration at 250° F. in API brine gives a decrease in viscosity with time until 10 days when a viscosity increase is observed. This viscosity increase is supported by the 280° F. studies. The 70.20.10DS.P43 solutions appear to crosslink or get thicker after 22 hours. This phenomena is not observed using the equivalent solution polymer, 70.20.10DS.7K. This indicates that there may be some differences in the emulsion and solution polymers.

The visual evaluation of crosslinked polymers for thermal stability is more difficult than the evaluation of the base hydrated polymers. The stability of the crosslinked gel is sensitive to the crosslinker, crosslinker concentration and polymer concentration in addition to the temperature. The crosslinked gels are evaluated on a scale as follows:

1. failure--no viscosity or precipitate forms;

2. 2 phase--separation of polymer and free fluid;

3. homogeneous--viscosity present but not a lipping gel;

4. lipping--crosslinked fluid which forms a tongue upon transfer;

5. rigid--crosslinked fluid which tries to retain its shape.

The initial testing of the thermal stability of the crosslinked gels is performed at 180° F. and is summarized in Table VIII. The polymers react with a variety of crosslinkers and are stable for extended periods of time at 180° F.

The crosslinked polymers are evaluated at 280° F. and 300° F. in API brine at 1 and 0.5% polymer concentrations. A concentration range of zirconium lactate crosslinker of 0.075 to 0.6 volume/volume % is used to evaluate these polymers. The results of these tests are given in Tables IX and X.

PROCEDURE

Stability tests on crosslinked polymers are performed by placing 100 g samples of hydrated base gels in 8 oz glass jars. The designated amount and type of crosslinker is added with a micropipette syringe. The jars are each sealed and then placed inside a purged pressure vessel with enough water placed inside the vessel to cover the sample level in the jar. The vessel is placed in an oil bath of the desired temperature for the required time period. The vessel is then removed and cooled to ambient temperature. The samples are removed and visually evaluated.

                                      TABLE VIII                                   __________________________________________________________________________     Thermal Stability of Crosslinked Gels at 180° F. in API Brine                   Polymer         Crosslinker                                                                            Time at                                                Concentration   Concentration                                                                          Temperature                                                                           Gel                                     Polymer (%)     Crosslinker                                                                            (%)     (days) Evaluation                              __________________________________________________________________________     50.40.10DS.6K                                                                          1.0     Potassium                                                                              .4      8      homogeneous                                             Pyroantimonate                                                 50.40.10DS.6K                                                                          1.0     Zirconium                                                                              .2      8      rigid                                                   Acetate                                                        50.40.10DS.6K                                                                          1.0     Zirconium                                                                              .4      8      homogeneous                                             Lactate with                                                                   Amine                                                          50.40.10DS.P24                                                                         1.0     Potassium                                                                              .4      .75    2 phase                                                 Pyroantimonate                                                 50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .2      .75    rigid                                                   Acetate                                                        50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .4      .75    rigid                                                   Lactate                                                        50.40.10DS.P24                                                                         1.0     Basic   .4      .75    2 phase                                                 Aluminum                                                                       Acetate                                                        50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .2      .75    rigid                                                   Oxychloride                                                    50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .4      3      rigid                                                   Lactate                                                        50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .4      5      rigid                                                   Lactate                                                        50.40.10DS.P24                                                                         1.0     Zirconium                                                                              .4      10     rigid                                                   Lactate                                                        50.40.10DS.P26                                                                         1.0     Zirconium                                                                              .4      3      rigid                                                   Lactate                                                        50.40.10DS.26                                                                          1.0     Zirconium                                                                              .4      5      rigid                                                   Lactate                                                        50.40.10DS.26                                                                          1.0     Zirconium                                                                              .4      10     rigid                                                   Lactate                                                        55.40.5DS.5K                                                                           1.0     Potassium                                                                              .4      8      homogeneous                                             Pyroantimonate                                                 55.40.5DS.5K                                                                           1.0     Zirconium                                                                              .2      8      rigid                                                   Acetate                                                        55.40.5DS.5K                                                                           1.0     Zirconium                                                                              .4      8      homogeneous                                             Lactate with                                                                   Amine                                                          55.40.5DS.P27                                                                          1.0     Zirconium                                                                              .4      3      rigid                                                   Lactate                                                        55.40.5DS.P27                                                                          1.0     Zirconium                                                                              .4      5      rigid                                                   Lactate                                                        55.40.5DS.P27                                                                          1.0     Zirconium                                                                              .4      10     rigid                                                   Lactate                                                        0.90.10DC.124                                                                          0.5     Zirconium                                                                              .2      2.8    homogeneous                                             Lactate                                                        0.90.10DC.124                                                                          0.5     Zirconium                                                                              .6      2.8    rigid                                                   Lactate                                                        0.90.10DC.129                                                                          0.5     Zirconium                                                                              .2      2.8    lipping                                                 Lactate                                                        0.90.10DS.123                                                                          0.5     Zirconium                                                                              .2      2.8    lipping                                                 Lactate                                                        __________________________________________________________________________

                  TABLE IX                                                         ______________________________________                                         Thermal Stability of Crosslinked Gels at 280° F. in API Brine                     Polymer  Zirconium Time at                                                     Concen-  Lactate   Temper-                                                     tration  Concen-   ature  Gel                                        Polymer   (%)      tration (%)                                                                              (days) Evaluation                                 ______________________________________                                         50.40.10DS.8K                                                                            .5        .15      2.8    2 phase                                    0.90.10DS.118                                                                            .5       .6        2      2 phase                                    0.90.10DS.118                                                                            .5       .6        1      2 phase                                    0.90.10DS.118                                                                            .5       .4        2      2 phase                                    0.90.10DS.118                                                                            .5       .4        1      2 phase                                    0.90.10DS.118                                                                            .5       .2        1      lipping                                    0.90.10DS.118                                                                            .5       .3        .9     2 phase                                    0.90.10DS.118                                                                            .5        .15      .9     homogeneous                                0.90.10DS.118                                                                            .5        .075     .9     homogeneous                                0.90.10DS.118                                                                            .5       .2        7      homogeneous                                0.90.10DS.118                                                                            .5       .2        14     homogeneous                                0.90.10DS.118                                                                            .5       .2        21     2 phase                                    0.90.10DS.118                                                                            .5        .15      7      homogeneous                                0.90.10DS.118                                                                            .5        .15      10     lipping                                    0.90.10DS.118                                                                            .5        .15      14     2 phase                                    0.90.10DS.118                                                                            .5       .1        7      homogeneous                                0.90.10DS.118                                                                            1.0      .6        .9     lipping                                    0.90.10DS.118                                                                            1.0      .4        .9     lipping                                    0.90.10DS.118                                                                            1.0      .3        .9     lipping                                    0.90.10DS.118                                                                            1.0       .15      .9     lipping                                    ______________________________________                                    

                  TABLE X                                                          ______________________________________                                         Thermal Stability of Crosslinked Gels at 300° F. in API Brine                    Polymer  Zirconium Time at                                                     Concen-  Lactate   Temper-                                                     tration  Concen-   ature  Gel                                         Polymer  (%)      tration (%)                                                                              (days) Evaluation                                  ______________________________________                                         0.90.10DS.118                                                                           .5       .3        0.9    lipping                                     0.90.10DS.118                                                                           .5       .3        1.8    2 phase                                     0.90.10DS.118                                                                           .5        .25      0.9    lipping                                     0.90.10DS.118                                                                           .5        .25      1.8    2 phase                                     0.90.10DS.118                                                                           .5       .2        0.9    lipping                                     0.90.10DS.118                                                                           .5       .2        1.8    lipping                                     0.90.10DS.118                                                                           .5       .2        4.0    lipping                                     0.90.10DS.118                                                                           .5        .15      0.9    lipping                                     0.90.10DS.118                                                                           .5        .15      1.8    lipping                                     0.90.10DS.118                                                                           .5        .15      4.0    lipping                                     0.90.10DS.118                                                                           .5       .1        0.9    homogeneous                                 0.90.10DS.118                                                                           .5       .1        1.8    lipping                                     0.90.10DS.118                                                                           .5       .1        4.0    homogenous                                  0.90.10DS.118                                                                           .5        .05      0.9    homogeneous                                 0.90.10DS.118                                                                           .5        .05      1.8    homogenous                                  0.90.10DS.123                                                                           .5       .2        0.9    lipping                                     0.90.10DS.123                                                                           .5       .2        1.8    lipping                                     0.90.10DS.123                                                                           .5       .2        3.7    lipping                                     0.90.10DS.131                                                                           .5       .2        6.0    lipping                                     0.90.10DS.131                                                                           .5       .2        10.0   lipping                                     0.90.10DS.131                                                                           .5       .2        14.0   lipping                                     0.90.10DS.131                                                                           .5       .6        4.0    2 phase                                     0.85.15DS.132                                                                           .5       .2        4.0    lipping                                     0.95.5DS.130                                                                            .5       .2        4.0     homogeneous*                               0.95.5DS.130                                                                            .5       .2        4.0    2 phase                                     ______________________________________                                          *The sample contained 10% by weight 12-200 mesh dolomite.                

EXAMPLE 8

A vicinal diol containing polymer is prepared as follows. 100 g of a 1% active solution of a copolymer of DMAEMA and acrylamide in equal mole percentages are adjusted to a pH of 10 with sodium hydroxide. This solution is reacted for one hour at ambient temperature with 0.15 g of glycidol. The resulting reaction mixture (gel) is cross-linkable with zirconium lactate and shows better thermal stability than the starting DMAEMA-acrylamide copolymer when crosslinked with zirconium lactate. 

What is claimed is:
 1. A method of treating a high temperature subterranean formation comprising contacting said formation with a highly viscous gel formed of an aqueous fluid, a water soluble polymer containing crosslinkable vicinal diol groups and a crosslinking agent selected from the group consisting of water soluble salts and complexes of multivalent cations, said water soluble polymer comprising a copolymer containing a monomer having the structural formula: ##STR12## wherein R₁ is hydrogen or methyl;Y is oxygen of NH; R₃ and R₄ are independently methyl or ethyl; n is 2 or 3; and X⁻ is a halogen, sulfate, CH₃ SO₄ or CH₃ COO⁻.
 2. The method of claim 1 wherein said one or more other polymers are selected from the group consisting of N,N-dimethylacrylamide, acrylamide, methacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, N-vinyl-2-pyrrolidone and acrylic acid.
 3. The method of claim 1 wherein said water soluble polymer containing crosslinkable vicinal diol groups is a copolymer of MAPDMDHPAS and NNDMA.
 4. The method of claim 1 wherein said water soluble polymer containing crosslinkable vicinal diol groups is a copolymer of MAPDMDHPAC and NNDMA.
 5. The method of claim 1 wherein Y is NH, n is 3, R₁ is methyl, R₃ and R₄ are each methyl and X⁻ is sulfate.
 6. The method of claim 1 wherein Y is NH, n is 3, R₁ is methyl, R₃ and R₄ are each methyl and X⁻ is Cl⁻. 